Electric-switch contact.



Witnesses L. L. TATUM. ELECTRIC SWITCH CONTACT.` APPLIATION FILED AUG.27, 1907.

Patend 0c.8,1912.

` Contacts, of which the following isa full,

great, the oil film which occurs between the recesses formed in thecontact faces, the oil -secured between the contact faces, wherebyUNITED STATES PATENT @il llhl.

LEWIS L. TATUM, 0F MILWAUKEE, WISCONSIN, .ASSIGNOR TO THE CUTLER-HAMMERMFG. CO., 0F MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

To all Iwhom, it may concern:

Be it known that I, LEWIS 'L. TATUM, a citizen of the United States,residing at Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented-new and'- useful Improvements inElectric-Switch clear, concise, and exact description, reference beinghad to the accompanying drawf in forming a part of lthis specification.

y invention relates to improvements in electric switches andparticularly to contacts for such switches. It applies particu larly toswitches in which the contacts are immersed in oil.

Heretofore the faces of the switch have been smooth 'and when thecontacts werey brought into engagement, a thin film of oil, remainedbetween the same, thereby causing' a high resista-nce contact. Due tothis fact arcs formed which burned the contacts andy caused them todeteriorate. One of the objects of my invention is to, form the contactsof a switch'in 'such a manner that when the contacts are moved into'lengagement the oil film will be practicallyf eliminated.

In accordance with the preferred form of my invention, I vproviderecesses in the contact -face of at least one of the contacts. Due tothis construction when the contacts are brought into engagement the oilwhich may be between the contacting faces. is squeezed or rubbed frombetween the faces and into the recesses, thereby eliminating the oilfilm, which has previously existed between the contacts.

When the contact faces are made smooth as has been previously done,owing to the fact that the crea of the contact faces is so contact facescould not be squeezed or rubbed out. By my construction, duc to the Hlmwhich tends to form between the contact portions or contact faces of thecontacts may be readily squeezed or rubbed into the recesses.Accordingly a close engagement is the current will be carried betterthan in the old form of contact, and arcs will be eliminated during theengagement of the contacts.

For the purpose of disclosing my invcntion, I have illustrated in theaccompany- .ing drawing, one embodiment thereof.

Specification o! Letters Patent.

Application led August 27,

rnrenteaoee. s, 1ere. 1907. Serial No. 390,399.

cordance with my invention, the oil easing of said switch beingf shownin Section. Fig. f2 is an underside view of the stationary arcmgcontact, and Fig. 3 is a plan view of the moving arcing contact.

Although .I have illustrated in the accompanying n rawing for thepurpose of disclosing my invention, one use of the same, it will beundeistood that the invention may be applied in various othercapacities'.

ln the electromagnetic switch illustrated, .l preferably provide analternatinw current magnet having a frame 1, in whidli is'supported theusual electro-magnetic Winding 2. This frame is supported upon a coveror head 3 having upwardly extending lugs 4, by which it is adapted to beattached to any suitable base.

The switch parts are all mounted beneath the cover or head 3, upon 'aninsulating block 5 which depends from the cover or head 3, and issecured thereto by vsuitable bolts 6. The movable member of thebwitch ismounted upon a stationary terminal member 7 secured to the insulatingblock 5b a bolt 8, and having a suitable terminal socliet 9 providedwith screws 10, into which is adapted to tit the end ot' one of theconductors. The movable member of the switch comprises a main contacterbrush 11, an auxiliary contact 'l2 and an arcinplr contact 13. rlhe mainContact is slightly flexible so that, when it engages the stationarycontact member of the switch, it will rub over the contact plate, and ispreferably made of laminations or leaves Jfastened in a cup 14.

The auxiliary contact is preferably mounted upon a flexible or springarm l5, and takes the form of a .roller 16 adapted to make u rollingengagement with the cont-act plate.

The arcing Contact 1,3 is preferably pivotedV upon a spring arm 1 8which, when the switch is open rests against a stop or plate 19,Whichprevents the arcing contact from coming into engagement lwith theauxiliary contact. The main contact ll, the arm 15, the plate lll, andthe arm 18 are preferably carried upon an arm 20, pivoted upon thesupport.

7, and are clamped iu position upon said pivotcd arm by means of a nut2l. In order that the arm lll may be relieved of. carrying current whichwould tend to deteriorate the Sti titl

spring thereof, lt provide e 14 and the arcing contact 3 3, and which isadapted to carry the current. The pivoted arm 2O is provided with anupwardly extending member gilt, adapted to pass through a centralopening 5t cut in the oloclt 5, and be pivotally connected to a link 23,which at its opposite end is pivotally connected with the core Q4 of thesolenoid 2. Thus when ythe solenoid winding is energized, the arm. 20will be raised and will carry with it the various movable contacts ofthe sa/itcl'in Ylhe Ystationary contact of the switch cornprises astationary Contact plate 25, having a terminal socket 26 similar to theterminal socket 9, and provided with a removable arcing Contact plateThis arcirig eontact plate is preferably secured in position by 'meansof a clamp 27, and is adapted to be engaged by the arc-.ing contact i3.

lThe various contacts are all inclosed in an oil casing 28, which issecured to the casing head 3 by suitable screws Q9 which are con-`nected to the casing and extend through the head, nuts 3# being;provided on the screws to maintain the casing in position. The casinglis lled with oil whereby all of the contacts operate in an oil bath.

lt has been found that, where switch contact's which operate in oil havethe faces there of comparatively smooth, an oil lihn forms between thefaces, thereby causing a high resistance Contact and tending to formarcs which burn and cause the deterioration of .the contacts. l havetherefore provided the 'arcing' contact 13 and the arcing Contact plate26a With recesses or slots 3l, which extenddiagonally across the facesoit the members, whereby as the two members en gage, the film oioil maybe readily pressed into these recesses, permitting a clean contact to bemade. ln practice, l prefer to have the grooves in one contact sodisposed that they will intersect the grooves iii the other contact, andhave so villustrated the same.

While l have described the recesses as being formed in the arcingcontacts it will be understood that like recesses may he fieaible comdoctor 5,22, which extends ,hetween'the cup' i meeste two Contactmembers Wherever Whether they form termed :in desired, irrespective ofareing or rhein contacts.

Having thus described l claim. as new and desire ters Patent, is:

l. A pair of coperatingswitch contacts each havinga rigidcontact facewith a plurality et grooves therein, the grooves in one Contactextending angularly to the grooves in the other contact.

2. A pair of cooperating switch contact-s each 'provided with rigidcontact tace having a plurality of diagonally disposed grooves, thegrooves in one Contact being disposed to intersect the grooves in theother Contact.

3. laan oil vimmersed switch, cooperating switch contacts, the engagingface oi' one of said contacts comprising a plurality of substantiallyparallel rigid ribs spaced to forni open ended channels for conveyingthe oil away from lthe engaging-faces of said contacts when broughttogether 4i. Av pair of cooperating switch contacts the engaging surfaceof each Contact com` prising a plurality 'of rigid uninterrupted ribsspaced from one another throughout their entire length, the ribs of onecontact extending at an angle to the ribs oit the other contact.

5, in an oil immersed switch, cooperating contacts, one ot' saidcontacts having one or more grooves therein for conveying theoil awaytrom the engaging faces of said contacts when the switch is operated,

t3.- ln an 4oil immersed switch, co fontacts each provided with a rigicontact face having,- one or` more grooves formed therein for conveyingthe oil away from. the

my invention, what to secure by Leterating engaging faces o saidvcontacts when the switch is operated.

ln Witness whereof, scribed my naine in the presence of two WitnessestLewis L. 'rs'roit l have hereunto sub-

